00:01
I want to write a function rule for a quadratic formula that has a vertex at the point 4 -1 and goes through the point 1 .28.
00:16
To do this, i need to know the vertex form of a quadratic function, so f of x equals a times x minus h squared plus k, and we remember that my vertex is the ordered pair, h, comma, k.
00:32
The first thing i'm going to do is take that vertex and plug it in for my h and k.
00:40
So that's going to give me f of x equals a times x minus h, which is 4, squared, plus k, which is 1.
00:51
Now that i have this, i need to bring in my ordered pair 1 .28.
00:58
This is going to help me find my a value.
01:01
So i've got my x and i've got my f of x and i'm going to go ahead and plug those in.
01:07
So i'm going to plug 28 in for f of x equals a times x is 1 minus 4 squared plus 1.
01:17
And i'm going to go ahead and simplify that...